package org.apache.commons.crypto.examples;


import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.Properties;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.crypto.cipher.CryptoCipher;
import org.apache.commons.crypto.cipher.CryptoCipherFactory;
import org.apache.commons.crypto.cipher.CryptoCipherFactory.CipherProvider;
import org.apache.commons.crypto.utils.Utils;

/**
 * Example showing use of the CryptoCipher API using a byte array
 */
public class CipherByteArrayExample {

  public static void main(String[] args) throws Exception {

    final SecretKeySpec key = new SecretKeySpec(getUTF8Bytes("1234567890123456"), "AES");
    final IvParameterSpec iv = new IvParameterSpec(getUTF8Bytes("1234567890123456"));

    Properties properties = new Properties();
    properties.setProperty(CryptoCipherFactory.CLASSES_KEY, CipherProvider.OPENSSL.getClassName());
    //Creates a CryptoCipher instance with the transformation and properties.
    final String transform = "AES/CBC/PKCS5Padding";
    CryptoCipher encipher = Utils.getCipherInstance(transform, properties);
    System.out.println("Cipher:  " + encipher.getClass().getCanonicalName());

    final String sampleInput = "hello world!";
    System.out.println("input:  " + sampleInput);

    byte[] input = getUTF8Bytes(sampleInput);
    byte[] output = new byte[32];

    //Initializes the cipher with ENCRYPT_MODE, key and iv.
    encipher.init(Cipher.ENCRYPT_MODE, key, iv);
    //Continues a multiple-part encryption/decryption operation for byte array.
    int updateBytes = encipher.update(input, 0, input.length, output, 0);
    System.out.println(updateBytes);
    //We must call doFinal at the end of encryption/decryption.
    int finalBytes = encipher.doFinal(input, 0, 0, output, updateBytes);
    System.out.println(finalBytes);
    //Closes the cipher.
    encipher.close();

    System.out.println(Arrays.toString(Arrays.copyOf(output, updateBytes + finalBytes)));

    // Now reverse the process using a different implementation with the same settings
    properties.setProperty(CryptoCipherFactory.CLASSES_KEY, CipherProvider.JCE.getClassName());
    CryptoCipher decipher = Utils.getCipherInstance(transform, properties);
    System.out.println("Cipher:  " + encipher.getClass().getCanonicalName());

    decipher.init(Cipher.DECRYPT_MODE, key, iv);
    byte[] decoded = new byte[32];
    decipher.doFinal(output, 0, updateBytes + finalBytes, decoded, 0);

    System.out.println("output: " + new String(decoded, StandardCharsets.UTF_8));
  }

  /**
   * Converts String to UTF8 bytes
   *
   * @param input the input string
   * @return UTF8 bytes
   */
  private static byte[] getUTF8Bytes(String input) {
    return input.getBytes(StandardCharsets.UTF_8);
  }
}

